import java.util.Scanner;

public class Demo21 {
    private static volatile int flag=0;
public static void main(String[] args) throws InterruptedException {
     Thread t1=new Thread(()->{
      while(flag==0){
    
      }
      System.out.println("t1结束"); 
 
    });
    Thread t2=new Thread(()->{
     Scanner scanner = new Scanner(System.in);
     System.out.println("请输入一个flag的值");
     flag = scanner.nextInt();
     System.out.println("t2结束");
    });
    t1.start();
    t2.start();
    t1.join();
    t2.join();
}
}
